Björn Wieslander

Left ventricular mechanical dyssynchrony by cardiac magnetic resonance is greater in patients with strict vs nonstrict electrocardiogram criteria for left bundle-branch block

BACKGROUND Left bundle-branch block (LBBB) is a marker of increased delay between septal and left ventricular (LV) lateral wall electrical activation and is a predictor of which patients will benefit from cardiac resynchronization therapy. Recent analysis has suggested that one-third of patients meeting the conventional electrocardiogram criteria for LBBB are misdiagnosed, and new strict LBBB criteria have been proposed. We tested the hypothesis that patients with strict LBBB have greater LV mechanical dyssynchrony than do patients meeting the nonstrict LBBB criteria, whereas there is no difference between patients with nonstrict LBBB and LV conduction delay with a QRS duration of 110 to 119 ms. METHODS Sixty-four patients referred for primary prevention implantable cardioverter-defibrillators underwent 12-lead electrocardiogram and cardiac magnetic resonance myocardial tagging. The patients were classified as strict LBBB, nonstrict LBBB, or non-LBBB (nonspecific LV conduction delay with a QRS duration of 110-119 ms). The time delay between septal and lateral LV wall peak circumferential strain (septal-to-lateral wall delay) was measured by cardiac magnetic resonance. RESULTS Patients with strict LBBB (n = 31) had a greater septal-to-lateral wall delay compared with patients with nonstrict LBBB (n = 19) (210 ± 137 ms vs 122 ± 102 ms, P = .045). There was no significant difference between nonstrict LBBB and non-LBBB (n = 14) septal-to-lateral wall delay (122 ± 102 ms vs 100 ± 86 ms, P = .51). CONCLUSIONS Strict LBBB criteria identify patients with greater mechanical dyssynchrony compared with patients only meeting the nonstrict LBBB criteria, whereas there was no significant difference between patients with nonstrict LBBB and non-LBBB. The greater observed LV dyssynchrony may explain why patients with strict LBBB have a better response to cardiac resynchronization therapy.

Localization of myocardial scar in patients with cardiomyopathy and left bundle branch block using electrocardiographic Selvester QRS scoring

INTRODUCTION Outcome of cardiac resynchronization therapy is severely worsened by myocardial scar at the left ventricular (LV) pacing site. We aimed to describe the diagnostic performance of electrocardiographic (ECG) criteria based on the Selvester QRS scoring system, first in localizing myocardial scar and second in screening for any non-septal scar in patients with strictly defined LBBB. METHODS AND RESULTS In 39 cardiomyopathy patients with LBBB, 17 with scar, 22 without scar, late gadolinium-enhancement cardiac magnetic resonance images (CMR-LGE) and 12-lead ECGs were analyzed for scar presence in 5 LV wall segments. The ECG criteria with the best diagnostic performance in detecting scar in each segment and in the four non-septal segments together were identified. Criteria for detecting non-septal scar had 75% (95% CI: 51%-90%) sensitivity, 95% (78%-99%) specificity, 92% (67%-99%) positive predictive value and 84% (65%-94%) negative predictive value. For each individual wall segment, 40%-60% sensitivities and 77%-100% specificities were found. CONCLUSIONS The 12-lead ECG can convey information about scar presence and location in this population of cardiomyopathy patients with LBBB. ECG screening criteria for scar in potential CRT LV pacing sites were identified. Further exploration is required to determine the clinical utility of the 12-lead ECG in combination with other imaging modalities to screen for scar in potential LV pacing sites in CRT candidates.

Specificity for each of the 46 criteria of the Selvester QRS score for electrocardiographic myocardial scar sizing in left bundle branch block.

BACKGROUND The Selvester QRS score consists of a set of electrocardiographic criteria designed to identify, quantify and localize scar in the left ventricle using the morphology of the QRS complex. These criteria were updated in 2009 to expand their use to patients with underlying conduction abnormalities, but these versions have thus far only been validated in small and carefully selected populations. AIM To determine the specificity for each of the criteria of the left bundle branch block (LBBB) modified Selvester QRS Score (LB-SS) in a population with strict LBBB and no myocardial scar as verified by cardiovascular magnetic resonance imaging with late gadolinium enhancement (CMR-LGE). METHODS We identified ninety-nine patients with LBBB without scar on CMR-LGE, who underwent a clinically indicated CMR scan at three different centers. The ECG recording date was any time prior to or <30days after the CMR scan. The LB-SS was applied and specificity for detection of scar in each of the 46 separate criteria was determined. RESULTS The specificity ranged between 41% and 100% for the 46 criteria of LB-SS and 27/46 (59%) met ≥95% specificity. The mean±SD specificity was 90%±14%. CONCLUSION Several of the criteria in the LB-SS lack adequate specificity. Elimination or modification of these nonspecific QRS morphology criteria may improve the specificity of the overall LB-SS.

ECG myocardial scar quantification predicts reverse left ventricular remodeling and survival after cardiac resynchronization therapy implantation: A retrospective pilot study.

INTRODUCTION Electrocardiographic (ECG) LV scar quantification may improve prediction of CRT response. METHODS AND RESULTS Data were abstracted in 76 patients who underwent a first CRT implantation at 2 US centers. Selvester QRS scar quantification was performed using the LBBB modified QRS scoring method. Seven clinical variables previously associated with reverse LV remodeling (RLVR) and QRS score were included in logistic regression analysis. Survival was compared across QRS score quartiles using Kaplan-Meier curves. RLVR occurred more frequently in patients with QRS score ≤ 5 (63%) than QRS score>5 (22%), (OR=5.83, 95% CI=2.11-16.07). After adjustment for clinical variables using logistic regression, QRS score>5 predicted RLVR (Chi-square=20.3, P=0.005, AUC=0.782). Patients in the lowest quartile of QRS score (<4) had improved survival compared to patients in the other QRS score quartiles (P=0.037). CONCLUSION ECG quantified LV scar predicts RLVR and long-term survival in patients with LBBB undergoing CRT implantation.

Evaluation of Selvester QRS score for use in presence of conduction abnormalities in a broad population.

BACKGROUND The Selvester QRS score is an electrocardiographic tool designed to quantify myocardial scar. It was updated in 2009 to expand its usefulness in patients with conduction abnormalities such as bundle-branch and fascicular blocks. There is need to further validate the updated score in a broader group of patients with cardiovascular disease and conduction abnormalities. We primarily hypothesized that the updated score could distinguish between presence and absence of scar by cardiac magnetic resonance imaging (CMR) with late gadolinium enhancement in 4 groups of patients with distinct conduction abnormalitites. METHODS A total of 193 patients were retrospectively identified that had received an electrocardiogram (ECG) and a CMR scan at Duke University Medical Center between January 2011 and August 2013: 62 with left bundle-branch block, 51 with right bundle-branch block (RBBB), 43 with left anterior fascicular block (LAFB), and 37 with RBBB + LAFB. Scar sizes estimated by ECG and by CMR were compared using scatterplots, modified Bland-Altman plots, and receiver operating characteristics curves. RESULTS Of 193 patients, 96 (50%) had no scar by CMR. The QRS score generally overestimated CMR scar. The area under the curve ranged between 0.62 and 0.65 for the different conduction types, and 95% confidence intervals included 0.5 for all conduction types. Performance was slightly improved in LAFB and RBBB + LAFB by excluding all points derived from leads V4-V6. CONCLUSIONS The Selvester QRS score for use in conduction abnormalities needs to be improved, primarily its specificity, to enable effective clinical use in a population with a wide range of left ventricular ejection fraction and low pretest probability of myocardial scar.

Selvester QRS scoring in conduction abnormalitites: Caution recommended due to recent findings.

The Selvester QRS Score, an advanced ECG tool that translates QRS morphology into information about myocardial scar, was expanded in 2009 to support use in presence of interventricular conduction abnormalities [1]. The Selvester 2009 QRS Score features one separate version each for left and right bundle branch block (LBBB and RBBB), left anterior fascicular block (LAFB), the combination of RBBB + LAFB, as well as left ventricular hypertrophy (LVH). The Selvester 2009 QRS Score also encompassed a slightly revised version of the original Selvester QRS Score for use in the absence of ECG confounding factors [2]. It has had renewed interest in recent years due to its potential in aiding patient selection for device therapies such as cardiac resynchronization. Initial results showed a good correlation (r = 0.66–0.80 depending on subgroups and area under the curve [AUC] = 0.93 across all conduction types) between ECGand cardiac magnetic resonance imaging (CMR) estimated scar extent in small cohorts of patients with high pre-test probability for scar in all conduction abnormalities [3]. Further, results indicated that the LBBB version provided information about scar localization [4]. We recently put the Selvester 2009 QRS Score to a challenging evaluation in larger, less carefully selected cohorts of patients in the various subgroups of interventricular conduction abnormalities [5]. Again, CMR was used as reference standard for scar presence and extent. In all conduction types, the Selvester 2009 QRS Score had a low level of discrimination between scar presence and absence — AUC was 0.62–0.65 depending on conduction type, and 95% confidence intervals included 0.5 in all subgroups. Intra-class correlation coefficients (ICCs) ranged between 0.16 and 0.45 across the conduction types, indicating poor-to-moderate agreement between ECGand CMR estimated scar extent. Furthermore, in this issue of the Journal, we report the evaluation of specificity for identifying scar using the Selvester 2009 Score in LBBB [6]. Specificities were evaluated for each ECG criterion and on a per-subject basis. In patients with strict LBBB according to Strauss et al., [1], and absence of scar by CMR (n = 99), we found that a threshold of 5 QRS score points, corresponding to scar in 15% of the left ventricle, had a specificity of 54%. Furthermore, a specificity of 82% was acheived for a threshold of 7 points (21% left ventricular scar). According

Selvester scoring in patients with strict LBBB using the QUARESS software.

BACKGROUND Estimation of the infarct size from body-surface ECGs in post-myocardial infarction patients has become possible using the Selvester scoring method. Automation of this scoring has been proposed in order to speed-up the measurement of the score and improving the inter-observer variability in computing a score that requires strong expertise in electrocardiography. In this work, we evaluated the quality of the QuAReSS software for delivering correct Selvester scoring in a set of standard 12-lead ECGs. METHOD Standard 12-lead ECGs were recorded in 105 post-MI patients prescribed implantation of an implantable cardiodefibrillator (ICD). Amongst the 105 patients with standard clinical left bundle branch block (LBBB) patterns, 67 had a LBBB pattern meeting the strict criteria. The QuAReSS software was applied to these 67 tracings by two independent groups of cardiologists (from a clinical group and an ECG core laboratory) to measure the Selvester score semi-automatically. Using various level of agreement metrics, we compared the scores between groups and when automatically measured by the software. RESULTS The average of the absolute difference in Selvester scores measured by the two independent groups was 1.4±1.5 score points, whereas the difference between automatic method and the two manual adjudications were 1.2±1.2 and 1.3±1.2 points. Eighty-two percent score agreement was observed between the two independent measurements when the difference of score was within two point ranges, while 90% and 84% score agreements were reached using the automatic method compared to the two manual adjudications. CONCLUSION The study confirms that the QuAReSS software provides valid measurements of the Selvester score in patients with strict LBBB with minimal correction from cardiologists.

Diffuse Myocardial Fibrosis Reduces Electrocardiographic Voltage Measures of Left Ventricular Hypertrophy Independent of Left Ventricular Mass

Background Myocardial fibrosis quantified by myocardial extracellular volume fraction (ECV) and left ventricular mass (LVM) index (LVMI) measured by cardiovascular magnetic resonance might represent independent and opposing contributors to ECG voltage measures of left ventricular hypertrophy (LVH). Diffuse myocardial fibrosis can occur in LVH and interfere with ECG voltage measures. This phenomenon could explain the decreased sensitivity of LVH detectable by ECG, a fundamental diagnostic tool in cardiology. Methods and Results We identified 77 patients (median age, 53 [interquartile range, 26–60] years; 49% female) referred for contrast‐enhanced cardiovascular magnetic resonance with ECV measures and 12‐lead ECG. Exclusion criteria included clinical confounders that might influence ECG measures of LVH. We evaluated ECG voltage‐based LVH measures, including Sokolow‐Lyon index, Cornell voltage, 12‐lead voltage, and the vectorcardiogram spatial QRS voltage, with respect to LVMI and ECV. ECV and LVMI were not correlated (R 2=0.02; P=0.25). For all voltage‐related parameters, higher LVMI resulted in greater voltage (r=0.33–0.49; P<0.05 for all), whereas increased ECV resulted in lower voltage (r=−0.32 to −0.57; P<0.05 for all). When accounting for body fat, LV end‐diastolic volume, and mass‐to‐volume ratio, both LVMI (β=0.58, P=0.03) and ECV (β=−0.46, P<0.001) were independent predictors of QRS voltage (multivariate adjusted R 2=0.39; P<0.001). Conclusions Myocardial mass and diffuse myocardial fibrosis have independent and opposing effects upon ECG voltage measures of LVH. Diffuse myocardial fibrosis quantified by ECV can obscure the ECG manifestations of increased LVM. This provides mechanistic insight, which can explain the limited sensitivity of the ECG for detecting increased LVM.

Evaluation of the ECG based Selvester scoring method to estimate myocardial scar burden and predict clinical outcome in patients with left bundle branch block, with comparison to late gadolinium enhancement CMR imaging

Myocardial scar burden quantification is an emerging clinical parameter for risk stratification of sudden cardiac death and prediction of ventricular arrhythmias in patients with left ventricular dysfunction. We investigated the relationships among semiautomated Selvester score burden and late gadolinium enhancement‐cardiovascular magnetic resonance (LGE‐CMR) assessed scar burden and clinical outcome in patients with underlying heart failure, left bundle branch block (LBBB) and implantable cardioverter‐defibrillator (ICD) treatment.

Ejection fraction in left bundle branch block is disproportionately reduced in relation to amount of myocardial scar

INTRODUCTION The relationship between left ventricular (LV) ejection fraction (EF) and LV myocardial scar can identify potentially reversible causes of LV dysfunction. Left bundle branch block (LBBB) alters the electrical and mechanical activation of the LV. We hypothesized that the relationship between LVEF and scar extent is different in LBBB compared to controls. METHODS We compared the relationship between LVEF and scar burden between patients with LBBB and scar (n = 83), and patients with chronic ischemic heart disease and scar but no electrocardiographic conduction abnormality (controls, n = 90), who had undergone cardiovascular magnetic resonance (CMR) imaging at one of three centers. LVEF (%) was measured in CMR cine images. Scar burden was quantified by CMR late gadolinium enhancement (LGE) and expressed as % of LV mass (%LVM). Maximum possible LVEF (LVEFmax) was defined as the function describing the hypotenuse in the LVEF versus myocardial scar extent scatter plot. Dysfunction index was defined as LVEFmax derived from the control cohort minus the measured LVEF. RESULTS Compared to controls with scar, LBBB with scar had a lower LVEF (median [interquartile range] 27 [19-38] vs 36 [25-50] %, p < 0.001), smaller scar (4 [1-9] vs 11 [6-20] %LVM, p < 0.001), and greater dysfunction index (39 [30-52] vs 21 [12-35] % points, p < 0.001). CONCLUSIONS Among LBBB patients referred for CMR, LVEF is disproportionately reduced in relation to the amount of scar. Dyssynchrony in LBBB may thus impair compensation for loss of contractile myocardium.